Zinc Loss Inhibition in Phosphorus-Doped Zinc-Based Core-Shell Catalysts for Vinyl Acetate Synthesis

A phosphorus-incorporated, zinc-based core-shell catalyst was synthesized via an in situ method for selective coating. The catalyst showed excellent activity and stability for the vinyl acetate synthesis. Results indicated that the optimal activity (53%) was achieved when adding 5% of HEDP (Etidronic acid) to the RF solution during the core-shell preparation, followed by calcination at 650℃. Characterization showed that the addition of HEDP decreased the electron cloud density around Zn, enhancing the adsorption of acetic acid and reducing the adsorption of acetylene, which facilitated the reaction and improved the conversion rate of acetic acid. A stability test over 550 h showed that the activity decreased by about 3%; the Zn loss rate was 6.29% (0.011%/h). The loss rate for the catalysts without a phosphorous source and with HEDP was 0.031%/h and 0.025%/h, respectively. This indicates that the addition of HEDP effectively mitigates the Zn loss rate.